CD45 molecule in gamma delta T cell generation: Disruption of CD45 exon 6 does not affect V gamma 3 dendritic epidermal T-cell development

There are two distinct lineages of T cells: T-cell receptor (TCR) alpha beta-bearing cells (alpha beta T cells) and TCR gamma delta-bearing cells (gamma delta T cells). All of the alpha beta T cells and most subsets of gamma delta T cells develop in the thymus, It has been demonstrated that the protein tyrosine phosphatase CD45 plays a pivotal role in the intrathymic development of alpha beta T cells, Thymocyte maturation is arrested at the transitional stage from immature CD4+ CD8+ double-positive to mature CD4+ or CD8+ single-positive cells after CD45 exon 6 gene disruption, In this study, we examined whether V gamma 3 dendritic epidermal T cells (DETC), a subset of thymus-dependent gamma delta T cells uniquely residing in the murine epidermis, are altered in the CD45 exon 6-deficient mice, In situ immunolabeling on epidermal sheets demonstrated that the CD45-deficient mice had a normal density and immunophenotype of V gamma 3 DETC compared with the wild-type control mice. Reverse transcriptase polymerase chain reaction revealed that similar levels of V gamma 3 TCR mRNA were present in the epidermis of CD45-deficient mice and wild-type controls. Flow cytometry demonstrated no significant difference in the proportion of V gamma 3 T cells in the epidermis between the genotypes, In addition, V gamma 2 T cells, another subset of gamma delta T cells, were also examined by how cytometry. The frequency of V gamma 2 T cells in lymph nodes was normal in the CD45-deficient mice. Our results indicate that although CD45 is crucial for the development of alpha beta T cells, this molecule is not necessary for the thymic maturation of gamma delta T cells, including V gamma 3 DETC and V gamma 2 T cells.